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Uterus

Stromal tumors

Leiomyoma variants


Reviewer: Nat Pernick, M.D. (see Reviewers page)
Revised: 15 March 2012, last major update February 2012
Copyright: (c) 2002-2012, PathologyOutlines.com, Inc.

Variants: apoplectic,   benign metastasizing,   cellular,   cotyledonoid,   disseminated,   epithelioid,   hydropic,   intravascular,   leiomyomatosis,   lipoleiomyoma,   mitotically active,   myoma nascens,   myxoid,   pallisading,   parasitic,   retroperitoneal,   symplastic


Apoplectic leiomyoma

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General
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● Hemorragic cellular leiomyoma, associated with birth control pills and pregnancy (Int J Gynecol Pathol 1988;7:212)
● 3% of leiomyomas
● Presents with abdominal pain, fever and vomiting
● Differential diagnosis includes use of tranexamic acid (cyklokapron), an antifibrinolytic agent used to treat menorrhagic, which may cause infarct-type necrosis and thrombosis (Am J Surg Pathol 2007;31:1215)


"Red degeneration" in leiomyoma associated with exogenous hormones

Micro description
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● Stellate zones of recent hemorrhage within nodules of hypercellular smooth muscle, rare mitotic figures (Am J Surg Pathol 1985;9:798)
● May have abnormal vessels of various sizes
● Often extensive coagulative necrosis


Apoplectic leiomyoma with extensive hemorrhage


Benign metastasizing leiomyoma

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General
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● May be a biologically distinct subset of leiomyoma, based on cytogenetic abnormalities (see below)
● Leiomyoma extends into vessels, migrates to lung or lymph nodes
● Original tumor must clearly be benign and sampled adequately
● Must rule out primary smooth muscle tumor of GI tract, retroperitoneum or other areas
● “Metastasis” may respond to hormonal treatment; may occur years after uterine resection
Symptoms: none, bleeding, frequency, pain or infertility
● Associated with spontaneous abortion, postpartum hemorrhage

Case reports
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● 50 year old woman with benign metastasizing leiomyoma associated with primary lung cancer 13 years later (J Med Case Reports 2011;5:500)
● 72 year old woman with extensively sampled leiomyoma with subsequent lung low-grade leiomyosarcoma (Arch Pathol Lab Med 1999;123:960)

Micro images
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● Benign smooth muscle cells; no atypia, no mitotic figures, no necrosis


Benign metastasizing leiomyoma with coexisting primary lung carcinoma

       
Uterine and lung tumors

       
Uterine and lung tumors

   
38 year old woman

Positive stains
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● ER, PR

Cytogenetics / molecular
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● 19q and 22q terminal deletion in 5 of 5 cases described (Am J Surg Pathol 2007;31:737)
● Metastatic origin from uterine primary can be documented by molecular methods (Hum Pathol 2000;31:126, Mod Pathol 2006;19:130)

Differential diagnosis
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Low grade leiomyosarcoma: atypia, necrosis, mitotic activity, infiltrative borders, micro RNA (Diagn Mol Pathol 2008;17:145)


Cellular leiomyoma

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General
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● Increased cellularity, no atypia and no mitotic figures
● Usually has large, thick walled blood vessels
● Same behavior as classic leiomyoma

Micro images
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Various images

   
H&E, CD10 and h-caldesmon

   
Tumor is well demarcated from and more cellular than surrounding myometrium; no nuclear atypia or mitotic activity is present

Positive stains
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● h-caldesmon, smooth muscle markers (Am J Surg Pathol 2001;25:253)

Differential diagnosis
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Leiomyosarcoma: infiltrative border, moderate to severe pleomorphism
Endometrial stromal sarcoma: infiltrative, often angiolymphatic invasion, h-caldesmon negative

Additional references
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Mod Pathol 2001;14:465


Cotyledonoid leiomyoma

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General
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● Also called dissecting cotyledonoid leiomyoma, Sternberg tumor (Am J Surg Pathol 1996;20:1455)
● Rare benign tumor characterized by extrauterine bulbous growth continuous with a dissecting myometrial component
● Grossly resembles placenta
● Median 40 years, range 23 to 65 years
● Dissecting leiomyomas rarely are due to noncotyledonoid variants (Am J Surg Pathol 1999;23:1032)

Case reports
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● 51 year old woman (Turk Patoloji Derg 2011;27:257)
● 55 year old woman whose tumor had alarming gross appearance (Arch Pathol Lab Med 2002;126:210)
● 63 year old woman with epithelioid variant (Arch Gynecol Obstet 2011;283:771)

Gross description
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● Multinodular, exophytic congested bulky tumor resembling placenta extends from uterine wall into broad ligament and pelvic cavity
● Red-brown with multiple bulbous processes protruding over uterine surface
● May dissect myometrium
● Not soft like malignancies

Gross images
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Fleshy polypoid tumor mass with multinodularity and cystic degeneration


Various images

Micro description
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● Fascicles and nodules of bland smooth muscle cells, prominent hydropic degeneration
● No necrosis, no mitotic figures and no atypia

Micro images
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Various images


Leiomyoma dissects into myometrium (black arrow) at the cornu; hydropic change is present around smooth muscle bundles (perinodular hydropic degeneration)


Desmin+


Disseminated peritoneal leiomyomatosis

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General
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● Rare, benign but pseudomalignant lesion of multiple peritoneal nodules < 2 cm that cover peritoneal surface, and clinically mimics disseminated abdominal carcinoma (Am J Surg Pathol 1980;4:197)
● Also called leiomyomatosis peritonealis disseminata
● Usually young women, associated with pregnancy (discovered at caesarean section), other altered hormonal conditions, endometriosis (Arch Pathol Lab Med 1984;108:669) or laparoscopic supracervical hysterectomy with morcellation for uterine leiomyomata (Genes Chromosomes Cancer 2010;49:1152)
● Nodules almost always regress spontaneously, but systemic chemotherapy has been suggested as a treatment option for rare cases of unresectable or metastatic tumors (Orphanet)
● Should rule out GI or retroperitoneal masses (GIST, leiomyosarcoma) before making this diagnosis
● Nodules are composed of fibroblasts and bland smooth muscle cells; decidual cells common

Clinical images
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Intra-operative appearance of nodules scattered over the peritoneum


Pelvic masses at laparoscopy


Numerous leiomyomas extending along the peritoneum

Gross images
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36 year old woman with intraperitoneal soft-tissue nodules

Micro images
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Various images

Molecular
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● May have cytogenetic changes associated with uterine leiomyomas (Genes Chromosomes Cancer 2010;49:1152)


Epithelioid leiomyoma

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General
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● Also known as clear cell leiomyoma, leiomyomblastoma (which may mimic smooth muscle cells of fetal uterus)

Micro description
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● Round epithelioid, rhabdoid and large vacuolated cells intermingled with spindled cells
● Clear or eosinophilic cytoplasm; no prominent nuclear atypia
● No tumor cell necrosis; no mitotic figures (Histopathology 2003;42:379)
● May have transition to typical smooth muscle

           
Various images

           
Various images

Positive stains
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● Desmin, alpha smooth muscle actin; also keratin

Negative stains
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● CD1a, HMB45

EM description
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● Various amounts of intermediate filaments; intermediate filaments and bundles of thin filaments without dense bodies often intermingled and occasionally form distinctive complexes with many irregular dense body-like structures and crystalloid bodies; also abundant mitochondria, some rough endoplasmic reticulum and free ribosomes (Histopathology 2003;42:379)

Differential diagnosis
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PEComa: HMB45+, CD1a+ (Ann Diagn Pathol 2008;12:401)
Carcinoma: has atypia, mitotic figures, tumor cell necrosis


Hydropic degeneration

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General
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● Edema fluid, collagen deposition
● Simulates leiomyomatosis or myxoid leiomyosarcoma
● May occur post-radiofrequency ablation of leiomyomas (Int J Gynaecol Obstet 2007;99:9)

Case reports
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● 48 year old woman (Pathol Int 2002;52:540)

Gross images
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Tan-white vaguely lobulated surface with multiple chalky-white calcified lumina

Micro images
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Perinodular hydropic change in leiomyoma

   
Prominent hydropic changes with marked edema and some cystic degeneration


Intravascular / intravenous leiomyomatosis

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General
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● Rare, mature smooth muscle grows inside lumen of uterine and pelvic veins or within the chambers of the heart (usually right heart)
● May arise from typical leiomyomas
● Clinically resembles low grade endometrial stromal sarcoma (minimal atypia, no coagulative tumor cell necrosis and usually 0-5 MF/10 HPF), except that gross involvement of veins is more prominent
● Excellent long term prognosis; rare distant metastases, may recur or embolize (Bol Asoc Med P R 2007;99:51)
● Cases underestimated because early diagnosis is easily missed; important to adequately sample all uterine leiomyomas and carefully examine the soft tissue on either side of the lower uterine segment below the peritoneal reflection to identify early-stage intravenous leiomyomatosis (Hum Pathol 2011;42:1240)
● May contain high levels of hyaluron (J Obstet Gynaecol Res 2010;36:454)

Gross images
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Intracaval smooth muscle tumor


Intravascular leiomyomatosis of uterus

Micro description
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● Elongated spindle cells vs. round/oval endometrial stromal cells
● Rare mitotic figures
● Hybrids with endometrial stromal sarcoma may exist

Micro images
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Intravenous leiomyomatosis

Positive stains
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● ER, PR (variable, Eur J Gynaecol Oncol 2004;25:362)

Molecular description
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● Breakpoint at 12q, similar to t(12;14) in uterine leiomyomas (Mod Pathol 2002;15:351)


Leiomyomatosis

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General
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● Also called infiltrating leiomyoma
● Rare, diffuse multinodular involvement of myometrium by numerous leiomyomas that are otherwise classic (Hum Pathol 2000;31:1429)
● Case report in 16 year old girl (first reported periodic case, Pediatr Radiol 2012;42:124)

Treatment
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● Uterine artery embolization (Eur J Radiol 2011 Dec 9 [Epub ahead of print]), GnRH analogues (Fertil Steril 2011;95:2434)

Differential diagnosis
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● Primary myometrial hypertrophy: uterine weight 120g without any myometrial lesion
Leiomyosarcoma: atypia and mitotic figures; hemorrhage and necrosis


Lipoleiomyoma

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General
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● 2% of all leiomyomas; combination of leiomyoma and mature adipocytes with benign behavior (Int J Gynecol Pathol 2006;25:239)
● Also includes neoplasms composed entirely of mature adipocytes
● May be due to adipose metaplasia in leiomyomas; does not appear to be degenerative, since adipose tissue has low proliferative activity by Ki-67 staining
● May give rise to liposarcoma (Am J Surg Pathol 2011;35:221)

Case reports
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● 50 year old woman with 8.5 cm tumor (J Midlife Health 2010;1:86)
● 57 year old woman with plexiform tumor with amyloid stroma (Arch Gynecol Obstet 2006;274:117)
● Intravascular uterine tumors (Hum Pathol 1989;20:252)

Gross images
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Pale yellow to bright yellow appearance

Intramural yellow tumor

Micro images
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Various images

   
With chondroid metaplasia

Positive stains
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● Adipose component: Ki-67 (low), ER, PR, S100, vimentin (Appl Immunohistochem Mol Morphol 2012 Jan 26 [Epub ahead of print])
● Smooth muscle component: K-67 (low), ER, PR, vimentin, desmin, α-smooth muscle actin


Mitotically active leiomyoma

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General
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● Usually young patients; often submucous leiomyomas with extensive necrosis that protrude into endometrial cavity
● Grossly and microscopically typical for leiomyomas, but 5-15 mitoses per 10 HPF (Am J Clin Pathol 1992;97:14)
● NO moderate/severe nuclear atypia, NO abnormal mitotic figures and NO tumor cell necrosis
● Typically benign behavior, but recurrence as leiomyosarcoma has been reported (J Obstet Gynaecol Res 2010;36:187)
Case reports: 56 year old woman taking tamoxifen for breast cancer (Taiwan J Obstet Gynecol 2006;45:167)
Treatment: myomectomy is usually adequate (Hum Pathol 1990;21:223)

Micro images
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Mitotically active leiomyoma of uterus

Differential diagnosis
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Leiomyosarcoma: usually marked atypia, coagulative cell necrosis, infiltrative


Myoma nascens

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General
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● Terminology only rarely used
● Leiomyoma that fills endometrial cavity, emerges from cervical canal as polypoid growth
● Has ulcerated surface, may be necrotic
● May resemble malignant tumors (J Obstet Gynaecol 2007;27:539)


Myxoid leiomyoma

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General
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● Islands of smooth muscle in myxoid connective tissue containing large vessels, but not infiltrative
● Small and bland nuclei (i.e. no atypia) and no mitotic activity
● Benign
● Myxoid leiomyosarcoma may arise in myxoid leiomyomas (Hum Pathol 2000;31:398)

Gross images
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Leiomyoma with myxoid degeneration in a 55-year-old woman

   

Leiomyoma with extensive myxoid degeneration; cut surface

Micro images
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Only very attenuated fascicles of smooth muscle cells can be identified


Smooth muscle cells are difficult to identify in this field but were numerous elsewhere

       
Myxoid leiomyoma of uterus


Myxoid leiomyoma with a marked pulmonary edema pattern


Leiomyoma with myxoid degeneration in a 49-year-old woman

Differential diagnosis
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Myxoid leiomyosarcoma: hypercellular, infiltrative, usually mild nuclear atypia


Pallisading / neurilemoma-like leiomyoma

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General
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● Resembles schwannoma, but are of smooth muscle, not Schwannian origin (Am J Obstet Gynecol 1977;129:389)
● More common in GI tract than uterus

Micro images
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Tumor cells line up in formations resembling the Verrocay bodies of neurilemmoma

additional image #1;   #2

Positive stains
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● Smooth muscle markers


Parasitic leiomyoma

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General
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● Present as peritoneal pelvic benign smooth-muscle masses separate from the uterus
● Likely originates as pedunculated subserosal leiomyoma which twists and torses from uterine pedicle
● As a “free” mass in peritoneal cavity, it survives by recruiting neovascularization from adjacent omentum, pelvic wall and other sites
● Associated with laparoscopic myomectomy and morcellation (Fertil Steril 2011;96:e90, Obstet Gynecol 2009;114:611)
● Typically does NOT refer to parasites associated with leiomyomas: Dracunculus / guinea worm in broad ligament (Am J Surg Pathol 1993;17:937), Schistosoma mansoni in leiomyoma (Clinics (Sao Paulo) 2007;62:529)
● Make diagnosis with great caution, because smooth muscle neoplasms arising in retroperitoneum and GI tract with recurring or metastatic potential are notorious for being bland and having no/few mitotic figures

Case reports
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● 28 year old woman with inguinal mass (Saudi Med J 2011;32:633)
● 35 year old woman with ovarian tumor causing infertility (Gynecol Endocrinol 2010;26:93)
● 51 year old woman with severely calcified mass that adhered to bowel wall (JSLS 2010;14:299)
● 52 year old woman with coexisting ascitis (Ethiop Med J 2003;41:363)

Clinical images
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Parasitic leiomyoma of omentum

Gross images
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Calcified mass



Retroperitoneal leiomyoma

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General
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● Usually women
● Resemble uterine leiomyomas, although distinct from uterus
● May occur years after hysterectomy or synchronous with uterine leiomyomas
● May arise from mesometrial smooth muscle (Virchows Arch 2007;451:899); probably are not parasitic leiomyomas
Treatment: complete resection
● Benign behavior; may recur locally
● Resemble classic leiomyomas with minimal mitotic activity
● Usually ER+, PR+

Case reports
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● 42 year old woman with 3 large retroperitoneal leiomyomas (Arch Gynecol Obstet 2009;280:499)
● 46 year old woman with 23 cm mass (J Med Case Reports 2011;5:578)
● 54 year old woman with mass arising from rectal wall (Obstet Gynecol 2003;101:1132)

Gross images
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Retroperitoneal leiomyoma

Micro images
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Retroperitoneal leiomyomas

Differential diagnosis
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Leiomyosarcoma: at least mild atypia, mitotic activity, ER and PR negative (Am J Surg Pathol 2001;25:1134)


Symplastic / Atypical / Bizarre leiomyoma

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General
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● Contains bizarre multinucleated tumor cells (moderate/severe atypia), less than 10 mitotic figures/10 HPF and NO tumor cell necrosis
● Associated with progestin use
● Benign behavior (Am J Surg Pathol 1997;21:1261), but rarely leiomyosarcomas may arise from them (Mod Pathol 2009;22:1303)

Gross images
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Bizarre leiomyoma

Micro images
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Atypical leiomyoma

Positive stains
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● p16 (85%), P53 (39%, Int J Gynecol Pathol 2009;28:529)

Additional references
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Mod Pathol 2000;13:328

End of Uterus > Stromal tumors > Leiomyoma variants


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